Some great answers (and boring ones) here but I'd like to think there is a few other things you need to do before making a purchase!
Don't be scared to google your company using different combinations search things like:
AWESOME HOST reviews
AWESOME HOST blog
AWESOME HOST good?
Fear not if you see some bad reviews but a lot of good ones some customers need a lot of TLC and when they don't get it they type the first hosting review site.
Newer hosting businesses (registered <1 year) need some extra attention but don't immediately dismiss them some smaller web hosts that opened months before have a personal touch and sometimes exceed expectations compared too days on end waiting times for support at competitors.
As for other factors any unscheduled downtime in 2017 is less than ideal and should be closely monitored as too how they will improve in the future and how they responded to it (but don't jump up and down for scheduled maintenance these things need happening be it software updates or hardware).
Anyway my apologies I just finished my shift so my grammar/spelling/makesense genes is not great but seen my email that i got accepted here.