You're very welcome.
5g is a great size for a betta.
I wouldn't go with the hex because betta's like shallow long water and the hex is narrow and tall.
The other one I don't know much about.. I know betta's need complete black out at night and the moonlight blue lights are a concern. Hopefully you can turn them off and they're not oddly connected to anything else like the filter.. some tanks have this..
Also I don't know anything about the filter.. types of media.. if it might be too powerful.. Several reviews did talk about it being surprisingly powerful and that it was too much for a betta.
I would probably put together my own kit. If you go to any fish store, including petco or petsmart you can get standard glass rectangular tanks for about $15. Usually they're by Aqueon. They look like this http://i2.photobucket.com/albums/y39/tnnsman7/lid.jpg
The hood is sold separately, but I have those glass hoods on all of mine. You could also opt for a black hood with light if you wanted, but bettas don't need or like direct light so it's not necessary unless you want to add plants.
As far as a filter you could go a few options. You could also not buy one. If you choose not to cycle the tank you will need once weekly 100% change at least, but I do highly suggest either adding a mid week 50% or doing the complete change day 5. I also suggest an airpump, airline, couple of control valves (placed in airline to turn down stone to a light mist) and an air stone placed underneath the heater. Otherwise you will have pockets of hold and hot water in your tank instead of even heating. Cost wise, it's probably about the same to cycle it as it is to get all of these things.
You could go with an Aquaclear 20:
This one has also gotten good reviews: http://www.amazon.com/Hagen-A285-Mar...qid=1363446697
Or to have complete biofiltration but not as much mechanical you could go with a sponge filter. There are many out there. Here is a popular one: http://www.amazon.com/ATI-SPONGE-FIL...rds=hydro+mini
Then you'd need a heater. I suggest one of these, in 50w:http://www.drsfostersmith.com/produc...m?pcatid=23952
For the first two I would turn the flow all the way down (it's adjustable). I would add a prefilter sponge on the intake so your betta cannot be hurt: http://www.amazon.com/s/ref=nb_sb_no...efilter+sponge
It will also add additional biolofical filtration. You only need to squeeze it out once a week in some of his old tank water after a change. It only needs to be completely replaced about once a year.
I would also sponge baffle the outflow by taking a piece of very porous sponge and a silicon or rubber band and attaching it around the outflow. I used this folded over personally but it's not the only one you can use: http://www.petco.com/product/113670/...er=22567628995
It just has nice big holes that slow down the flow and but do not. I don't even really rinse mine out with a water change, and I may never replace it unless it looks like it's wearing down.. so far so good since november. Fll the water that comes through it is already the cleaned/filtered water so it shouldn't get gunked up. You may give it a swish every month or few months if you notice the flow reducing.
Inside these filter are large sponges. These only need to be swished in the old tank water along with a water change, and only need to be replaced probably years, and no more than every 6 months. There is also a bag of black carbon that needs to be replaced monthly. Make sure you really rinse it very very well before placing in your tank because it will release a lot of black dust for a while. Or if you don't want to use carbon you can get an extra sponge and fill the space with it. I have done this. Others use carbon. I use it the first month and then switch to an extra sponge. Then there's a little bag of rocky stuff called biomax. It's just more surface area for the biological filter to grow. It should be maintained like the sponge.. wrinsed etc but only replaced infrequently.
Also only replace one type of media within a month of eachother and you should never have a breakdown.
Hopefully you already have one of these: http://www.amazon.com/Marina-Floating-Thermometer-
Then if you are cycling your tank you need gravel, but if you are not that is optional. You should have at least one good cave for your betta to hide in and lots of oversized soft plants, especially ones that reach all the way to the surface because that's where most bettas like to relax and sleep. Anything you get should be tested out by taking a pair of women's panty hose and dragging across and through. If anything catches it is too sharp for your betta. Especially check inside ornaments as sometmes there are rough spots. Sharp stems can be pruned and sharp ornaments can be sanded with paper that has never been used for anything else.
Oh and this is how you can do fish in and fishless cycling:
Fishless: Get a bottle of ACE Pure ammonia and an eye dropper. You also need a reliable drops kit for ammonia, nitrite and nitrate. Add 10 drops pure ammonia, wait 24 hours and test for ammonia. If it is at 4 ppm, wait another 24 hours and test again. If it's less than that add 10 more drops, wait 24 hours test. Basically you want to test every 24 hours and add another dose any time you see it below 4ppm. After about a week you can start testing for nitrites. The nitrites you ignore, but just keep track of. One day, after 24 hours, ALL ammonia will be gone to zero and you will be left with only nitrites. At this point, dose half - 5 drops a day to keep nitrites around 4 ppm. One day all the nitrites will vanish overnight to zero and you will be left with only nitrates. At this point I would keep dosing an extra couple few days to make sure all ammonia and nitrites still disappears within 24 hours - actually at this point it should all be gone by 12. Then you do a HUGE.. like 99.9% water change with your siphon all the way down to the gravel, but don't disturb the gravel. Fill it up with same temp water use the in tank thermometer to match temp, mix up buckets with conditioner than add so you don't shock your bacteria. Test your nitrates. If they are 5ppm or lower you're good. If they are still too high (mine took a 90% and 2 or 3 50%s) do more water changes until they're down low. From here fish can be acclimated and a once weekly 25%-50% with siphon should keep nitrates <20ppm.
Fish-in:You need to be testing daily with a reliable drops kit for ammonia and nitrite and doing an extra 50% change any time you see either. In addition to this a weekly 50% with siphon is needed. First you will see ammonia, then nitrite. Eventually, hopefully, you will see ammonia fall and stay at 0 even after a week of no water changes, and finally nitrite. At this point you will be left with only nitrates after a full week of no changes and these can be kept <20ppm by weekly 50% change with siphon
That's a lot.. let me know if you have any questions :)