i am currently using yahoo and am in the process of switching to hostgator. i have read some great things about hostgator on this board and also some negatives about them as well. yahoo had more problems than it was worth for me, many times i issues with my database that i just had no control over, i had to open a trouble ticket with yahoo and just wait for them to fix it. 24-48 hours was the normal time it took for them to fix the issue. um, i also have a small customer base, only about 40-50 active users and 10-15 on at any given time, and almost like clockwork the site would slow down on sundays all day and once or twice during the weekdays.
good luck

I would give this a look at.

http://a2b2.com/

If you have a large forum, you will run into mySQL connection limits on either HostGator or Yahoo. If you run a small to medium forum, both will work great for you.

You should probably answer these questions before I can help you:
1) How many domains?
2) Bandwidth, growth requirements?
3) How many databases?

Once you answer that then you can decide on shared, VPS, Dedicated, etc.

I was at netfirms and it was the biggest mistake I ever made, EVERYTHING about them is appalling. I moved to http://www.mjwebhosting.com/ and everything is fine now, he even did the move for me me so a big thumbs up.

He probably has a new host by now...