new tank questions!!

Hi just a couple of questions, i've got a corner tank thats been running for a couple of years and i'm now thnking of getting a better tank, i've seen 2 i like but i'm not sure which would be the better buy the first one is the Fluval 90 litre with fluvel 2 filter or the secound tank which is a Aquaone 620 which has a built in filter. the secound question is as i have gouramis will the tanks be suitable and how many could i put into the 90 litre.
Any help would be appreciated.

the gouramis i have are 2 pearls and 1 male dwarf and 2 female dwarf gourami, i just don't want to get a tank thats too small for them.

at the moment the tanks a bowfront corner tank and as i got it given to me without a box i can't be sure of how many litres it is but it's got to be about a 125 litres,i know it measures 2ft x2ft out from the corner on each side.

I got them from my lfs which sells lots of different gouramis like pearls, gold,sunset, dwarf and the blue dwarf, 1 of my females are blue and the other is silver, but i was told that i'm fine with just 2 males. I've not had any fry or bubble nests yet but i read they have to be at least a year old to begin breeding them, my male pearl is just starting to get the red colour on the belly so what sort of age could they be?
I will be using plants in the new 90 litre like i do in this tank but at the moment i only have 1 strip light and the new tanks have 2 i was thinking i might get the aquaone 620 does anyone know if the filter media are easy to use and how many places sell them?

I was told that the blue dwarf is a variety of the dwarf gouramis and the blue males have a red edge to the fins and tale. lfs had both types of gouramis i'll try and get a photo and post it later on