This is exactly what I am having the hardest time with! I keep going back to AKV because I like the theme so much more than SSR and can see a kid loving every minute staying there. I don't like the earlier expiration of BW to buy, but I want to stay here someday. The studio sizes at BLT were throwing me, but the more I look at pictures and the more I think of how easy a walk to the MK would be with a small child. Even if its a little more buy in, it does have cheap maintenance fees. That is the top of my budget. I won't spend any more than that. I just know we have gotten to where we like to stay deluxe and with how much it costs, I think this will be a good investment!
Would you "mind" staying at SSR if you can't get into another resort?
Most times you can get a studio or 1bd at akv (I believe std views are easiest to get but not sure), and to a lesser extent, BLT lake, most of the time. Bwv pool/garden is also usually an easier option. 1bds are also easier to procure than studios.
If you get SSR points, it won't hurt as much "financially" to use your points for a 1bd anywhere

Honestly? Your kid will like being at ANY deluxe resort.
When we stayed at poly, my 6yr old preferred the pool games over going to the parks. He insisted on being at the hotel at 3pm JUST so he could be at the pool.
For us, the remoteness of akv was very stressful. We ended up eating in the cafeteria every day, as it was too hard to leave the resort for dining purposes (our child was high maintenance). SSR would have been a better option bc at least you could walk to DD, now called Disney springs.
You are buying on the anticipation of what you THINK your future child might like

My older sister bought into BLT when her daughter was 5yrs old. By age 8, her kids ONLY preferred the Epcot/Boardwalk area. Her daughter is 14 now, and the last 6 years, my sister ONLY stays at the Boardwalk area bc that's the only place her kids want... So her BLT points are never used at BLT after the first 3 years (ages 5-8). Over the last 6 years (ages 8-14), it's been pretty much bcv or bwv.
Hope this helps provide perspective! Another alternative is to buy SSR, see how your child's preferences develop, and then sell/rebuy. Again, my older sister has been using her BLT points pretty much exclusively for Bwv or bcv over the last 6 years, so ....