Already own a 3DS, but at $299, the 3G PSV received an Amazon pre-order the instant I found they were available.

Already carry an iPhone everywhere I take a wallet and keys so dedicated gaming devices rarely leave the house (DSl, 3DS, PSP), but between the 3G connectivity and that OLED display, the PSV may be the first to go with me every time I have a laptop sling with me, pending whether the web functionality/browser is on par with the iPhone's.

I experimented with the new 3DS web browser for less than 10 minutes before determining that beween the low res screens, slow load times and WiFi tether, it's basically unusable unless absolutely no other web enabled device is available. Touch based v-keyboard makes it much more suitable than the PSP's (also virtually unusable), but there is still no comparison between it and even the limited but fully usable iOS Safari browser/iPhone.

You might be waiting awhile unless the PSV absolutely trounces the 3DS in sales.

Nintendo has already gone on record in response to PSV pricing in stating that they have no intention of deviating from their current 3DS pricing strategy. Meaning; no price cut imminent, contrary to popular belief. 

Can't say I agree with this strategy or whether it's driven by arrogance or delusion, but it does look as though they will be relying upon incoming Nintendo franchise games to continue to sell the 3DS at $249.

I may eventually get both, but the 3DS won't be for awhile (if ever).  I will most likely pick up Vita at launch. 

Here is my rationale:

1. Similar Battery Life

2. Similar Console Price

3. Similar Game Prices

It comes down to preference.  Would you prefer 3D with Wii visuals or the near PS3 graphics?  I prefer the better graphics right now since my PSP already has near Wii visuals.

And this is the real reason why many will still opt for a 3DS once the same franchises that were on the DS show up on the 3DS, even at $249. Certainly not because of the 3D, and certainly not because the hardware itself represents a better value by any measure of the word. 

As far as your rationale goes, you'd have a tough choice based on the 3 criteria you listed because the battery life will likely be about the same (not different enough to be a key factor), the hardware is the same price, and the basic retail games will also be the same price.

Library of scheduled titles and announced titles should be your best bet. 

3DS
Luigi's Mansion 2.
They could cancel Mario 3DS and Kart, release Nintendogs: Clean the Dogs, but I'd still buy a 3DS for Luigi's Mansion 2.
Plus, I'm bias.

Selected PSV only, but it may turn both someday:)

I'm pretty much ok with this. I waited 2 years to play new super mario wii, even though I had a wii all that time. The mario and zelda games are the only thing that interest me on nintendo gear these days. I'll also be playing with the 3D turned completely off.

If I have to wait 2 or 3 years before I get a 3DS, so be it.

Right now, I can't justify a purchase of either, but I want both. It took me years and a big discount from Circuit City (Liquidation sale) to justify getting a PSP, so it'll probably be a while.

I already have a 3DS.

I think the Vista is great. Sony did a really great job showing off how awesome it it, and it actually has a good chance of overtaking Nintendo in the handheld market.

However, their games don't interest me personally, so I'll be fine with a 3DS for a long while.

Hm... doesn't that mean you care a little?

OT: I'm buying a Vita day one, though I'll probably buy a 3ds too in 2-3 years just for pokemon games.