I would go for the 10g but know you'll spend more setting it up. The tank is just the start of things to come.
*You'll need a stand that will hold 120lbs+.
*You'll need the gravel at a rate of 1-2lb per gallon.
*You'll need more plants and more places to hide because it's larger. I sometimes pull silk plants off their base and float them at the top of the tank because my guys all like to sleep up top.
*You'll need a gravel vac.
*You'll want a filter of some kind. If you use an HOB you'll want to prefilter it and maybe baffle it.
*You'll need a lid
*You'll need a good 50-100w heater. I like Aqueon Pro (the black ones not the regular crappy line), Jager and Marineland Visitherm
*You'll need one of those in tank thermometers to monitor temps
*You'll need a drops testing kit for ammonia, nitrite and nitrate to cycle it (cycling will take up to 2 months)
*You'll need water conditioner
I think you're good to go then..
Vs. 2 gallon
*Stand needs to hold 30lbs
*Gravel is optional if you don't want to cycle - rate of 1-2lb per gallon is still fine if you want gravel
*filter is optional and I personally wouldn't use one unless it's a sponge filter
*Testing kit is optional so long as you're doing the two water changes a week - one 50% and one 100%
*Turkey baster will replace a vac
*You'll still need conditioner
*You'll need a 25w heater instead (jager or marineland visitherm)
*You'll still need a thermometer
*You still need a lid
*You'll still need appropriate plants/hiding places but it's a much smaller space.