I’d be hesitant to argue about relative quality of cassette decks. I’d say get something pretty good, but don’t spent crazy money on one.
I know you’re looking for the best transfer possible, but the fact of the matter is that old cassettes are not great sources for quality audio. They were convenient and cheap, but you didn’t buy them for how good they sounded.
In mp3 terms you are talking about 128kbps quality. That’s commercial recordings. If your tape is non-Dolby it was probably home recorded, so that number is much lower. Maybe half.
Dolby Noise Reduction helped with one of cassette tapes’ biggest weakness: tape hiss. Roughly speaking DNR tapes added a volume boost to the frequencies where tape hiss is strongest. On playback the DNR would then cut the volume of those high frequencies and you’d perceive a better signal to noise ratio than you would have without it.
Pretty much all reasonably good cassette decks should have DNR built in and a button for turning it on or off. So if your tape wasn’t recorded with it, you won’t lose those high frequencies as long as you disable it.