As above, I have a Hagen magnet and I personally find it useless, and it un-plants my hc everysingle time.
what do you use? what would you recommend?

I use one of those things used to clean car windows; you might find one at a Dollar Store or a Wal-Mart, but I would recommend something of a little higher quality like a Canadian Tire

Otos, or a razor blade based scraper like the one made by Tetra.

I've 7 otto's in a 10 gallon tank and they're pretty useless, i'll invest in the razor, thank you

I like to use a two sided sponge when I clean my 75 gallon. For the trickier places I prefer the use of a razor blade as mentioned above. Although my two chinese algae eaters are doing a great job with most the plants I find they have trouble eating the the small algae formation on the bottom of the tank. This is when I bought an algea killer solution.
Although this helps a lot, my plants are growing slower than usual due to the lack of water hardness. So I compensate by using peat moss around the base of each plant. Most of them love this, especially the amazon swords and the cryptocorynes.

I use the Tetra tec scraper and love it tbh. Makes cleaning look effortless.

For cleaning the bottom of the tank near the sand try an old toothbrush this way the glass won't get scratched as the sand particles fall right through the brush. Its the best I have found so far.

sponge cleaning always work for me

Razor for me too, though I wish it were wider Also use a bit of corse filter sponge tie-wrapped around the other end of my razor scraper for the bow front on one of my small tanks.

I use a regular Scotch scrub sponge. Seems to work great on glass. You would never use this on Acrylic however.

I use one of those JBL blanki on a stick things, a floaty magnet and also a toothbrush. If you leave it too long, algae is always a pain to shift.