If you're looking for power, which many do, the SSEi will be the better choice (though the NA engine has good power too). As stated, Series 1s don't have a huge aftermarket like the Series 2, but they still have PLENTY of potential.
The SLE is an option package, a step up from SEs, but are not supercharged except for the few rare ones that are. They have sportier body cladding than SEs, as do SSEi'*. They have the extra options which can include leather seats, HUD, sunroof, etc.
I love the 92-95 body style. 96-99 had a bit more refined styling, but for the most part they are the same inside and out as the 92-95, except for the Series 2 engine.
The 2000+ body style is much more aggressive, especially the SLE and SSEi. The interior is nicely improved over the previous years, and the ride and handling is better as well.
The seats ARE more comfortable from 92-99, especially the "AL7s" which are the 9-way (or 12-way) power seats. But I prefer the LOOK of the seats in my 2003. They are comfortable enough too.
There are a lot of things to consider if you're looking for a Bonne. Deciding what engine you want is a good first step. Since you have a GTP, my guess is you'll want the SSEi.