I'm using a few Deltran Battery Tender Plus
Most of the fellas I ride with use the Deltran Battery Tender Jr.
In a pinch, when I was 1 short, I used the HF battery float maintainer for about 2 years on one of the wife's bikes till I got round to getting another Deltran - for on sale for under $10, I have to say it did the job. A bike I sold about a year and a half ago, I let the buyer have that HF maintainer figuring he would use it for a little bit until he'd find something better - few weeks ago when I talked to him, he's still using it and said the same battery is in the bike when I sold it to him. I really can't complain for something that was under $10 for getting the job done.
I've used a couple HF maintainers for a boat, now long gone, and have to say the HF maintainer did its job there too.
And one of my workers is using the HF maintainer on his bike.
I keep a couple new in the box HF maintainers just in case some day I have a use.