Miracle Tubes are the benchmark. I've had the best luck with them too. 54" ones I believe. Any of these tubes are only as good as their stake though, dont skimp on that. If your area gets any wind at all either a steel T post or rebar is your best bet. I've tried everything and those are the best, MAYBE 2" conduit too.
I've had fantastic luck finding old steel t posts around local farms. Most guys just pile them up out back and will give them to you. I have posted on the local town FB pages and had plenty of guys that just want them out of the way, or for like $2/ea. Now I just scoop them up and stockpile when an opportunity comes along. Its funny how many you start finding when you're actually looking for them. Just dont be cheap and skimp on the stake. Best of luck!