If you want something that you can carry with you, whether around the house or in a vehicle, without being tied to a power cord from an ac adapter or dc cord in your car/truck, then a handheld is your pick. A handheld has the additional advantage of being operable from batteries (in the house) in the event of a power outage.
However, I believe the 996 is a bit more sensitive than the 396. Audio, in the larger, base/mobile style case, is better, as would be expected (not that the 396 audio is bad, but the base type units usually sound better as a class). The display on the 996 is also larger.
A couple of other points for the 996 vs the 396: It has a 250 talkgroup limit per system, vs 200 for the 396. For large trunked systems, that can be a plus. The 996 can also handle muti-site trunked systems, something the 396 does not do readily. The Pima County P25
system I mentioned in your earler inquiry shows two sites, but comments indicate it may be tied into other systems in the area at some future date. Multi-site would be very useful in that case. I have not had intermod issues with my 396, using it where ever I go in the metro area. No issues with the 996 either, but I'm using it as a base, not mobile. Price on the two scanners, from most online retailers, is approximately the same.