Hello and welcome. Like others who responded, I've been busy for a few days and didn't know you were here. I still work for a living... not like a lot of these "rich" retired folks who live full time in their RVs.
I too spent months searching and finally made it around to the 3950 and 3914, just like you. Absolutely loved the 3950 layout, particularly the opposing sofa and seat in the living area. Also liked the second 1/2 bath but finally decided on the 3914 for these reasons.
First, my most critical need was a 14' garage (for reasons I won't go into now). Decided I just couldn't live with a 12' garage.
Second, after weeks of carefully reviewing the floorplans, these are the specific features of the 3914 that appealed to me the most.
Probably the most important feature was the dual entry into the bathroom. Think of this: If one of you is ill, and in bed, do you want someone else constantly going through the bedroom to get to the bathroom? Or, wouldn't it be nice if one of you wants to sleep a little later to not be disturbed as much by someone else going into the bathroom or having a shower? (But now that I think about it, the 3950 might have had a sliding door to separate the bedroom too, don't remember for certain. I know the competition's units didn't have this.)
And the REAL stairs leading up to the loft! No comparison to the rickety metal ladders of most models and even the 3950's nice built-in wooden (and attached) ladder. If you haven't had a chance to actually climb the stairs of the 3914 you need to do that. Much safer and more comfortable.
Also definitely liked the three slide out feature compared to the two slide feature.
Both units have hookups for washer/dryer. The 3950 has it in the closet in the bedroom and the 3914 has it underneath the REAL stairs, accessible from the garage. The hookup is plumbed at the factory with its own separate holding tank and dump valve (in the 3914).
I actually bought my 3914 sight unseen. Hadn't even set foot into a real-live unit. Did all my research online and in brochures. So far I've only driven it from the dealer to my home (a little over 1000 miles) and spent two nights in it but I'm very happy with it.
Obviously, you have to find the right match for your needs, the 3914 was right for me.
You didn't say if you have children (I don't). If so, the extra 1/2 bath may be very handy for you. If no kids, and if you have a use for the 14' garage, then perhaps the 3914.
Check your overall weight. I seem to remember the 3914 is a little heavier than the 3950 which means it will reduce your gas/diesel mileage.
Both are excellent units!
Whatever you finally choose, you might want to consider an alarm system. I recommend you check x10.com as they have some great wireless systems for under $100.00 that give you enough sensors for every door and storage compartment, propane tank doors, generator doors, etc. You never know who's lurking around your unit at night when you're sleeping and in case you hadn't already heard, virtually all RV exterior storage compartments share the same key sets so everyone else out there has your keys. (Don't worry about the entry doors, they are unique.)
Hope this is helpful.