I've got a cheapie Canon MG2950, it's a top rear loader, takes max of 5 envelopes at once. Won't print on thicker card, and won't print photos on A4, it restricts the size when photo is chosen as the type of paper loaded.
I didn't know that when I bought it.... I should have read the manual LOL.
My advice is don't just read the advertising blurb for any that you are considering, download the manuals and check it will do all that you want it to do.
Really miss my old MP510 and the one I had before that.