I'm doing trial periods at fastmail, zoho and namecheap (fronting for titan ).
Zoho will fail back to a low volume, web only version if the bill doesn't get paid while the others just stop working.
Those were pretty much the top three I found across all the "top 10" reviews I could find -- aside from the ones that obviously cater to spamming (marketing) customers.
Would love to see reasons for/against them.
How about fastmail? I'm on a demo account with them right now -- with the exception of some relay restrictions that are especially annoying, it seems a good option, but I'm not familiar at all with them.