Model A for: cheaper to buy now, the 4 banger "thump", great idle sound on open pipe, love the light 4 block. Reliability? Against: less room in sedans? not much else.
V8: the 8 cylinder zip, great sound on open pipes (look, I can like them both OK?), synchro box, better brakes. I prefer the styling of the '32-'34 Fords, but that's just a personal thing. I don't think the Model A rad shell is so handsome. The only negative of the V8 is will your block be cracked, its all I can think.
Probably not for here, but I would be interested in a discussion as merits of the 4/8 layout for power. The 2 blocks are not far off same capacity, and a warmed up 4 can easily produce 80hp, but is it harder to squeeze more power out of a small 21 studder without losing bottom end grunt?
Tom.