I would go with option #1 as well, I don't like the HOT Magnum and the Eheim 2026 would defintely be overkill on a 20 gallon. Option #1 with the the XP1 would be the easiest to service and would be the least expensive. I would personaaly go with the Eheim 2213 with that option because Eheims are such high quality, but since you want ease of maintenance and good quality, the better choice overall would be option #1 with the XP1.
Also stick with the AC300 as opposed to the AC200 since it gives you more room to upgrade and it will fit over the rim of more large tanks. An AC200 will not fit over the rim of my 40 gallon Hagen tank.
Also stick with the AC300 as opposed to the AC200 since it gives you more room to upgrade and it will fit over the rim of more large tanks. An AC200 will not fit over the rim of my 40 gallon Hagen tank.