I don't think the argument should be are multiple cores better than one. If you're only doing some web surfing, some YouTube, and e-reading on a tablet, with some lightweight games, a single core processor works just fine. Basically, the casual user probably isn't going to miss extra cores. I've seen people get swotty about multiple cores lately, which might make tablet novices feel pressured into feeling like they have
to get multi-core because some tech guy on a forum or blog said so.
Other people on here have been quite sensible with the argument: What is it you want from your tablet? A1 and Fire are comparable in several aspects. If you want Market, Netflix, and basically an open ecosystem and a good screen at a budget price, then the A1 is great (yes it has the SD card). If you want cheaper and don't mind being tied to and tracked by Amazon, then get the Fire. If you want the Fire and are comfortable trying to hack it, then good for you.
Someone mentioned Coby:
I don't want a Kindle or Amazon tie-in. I've had a Coby 7024 before I had internal memory failure. I got it for $161, and I liked it for the most part. Side-loaded Market and it worked for a little bit before getting buggy. I didn't have too much trouble with the resistive screen, and ereading was okay in it (PDFs in 7inchers do not display well). It ran Froyo. Aside from the self destructing memory, I discovered that you need a good resolution to really enjoy ereading on an LCD. I'm now reading books on my work tablet (Galaxy) and it's a lovely ereading experience, for me as easy as e-Ink if not better, but the 10.1 inch tablet isn't as comfortable as the 7-inch.
I decided to replace it with the A1, even though I had to increase my budget. However, Tuesday night I convinced a Coby rep to sell me the 16GB for the 2GB price. :-D After I pestered him with questions. I'm banking some of my money on Lenovo's quality in general. We have ancient Thinkpads still chugging, they're just too outspec'd to be of any real use.