I use this one:
however any humidifier which takes water bottles will let you avoid the 'gross tank' problem. Rinse out the bottles after use, spray some 70% rubbing alcohol in them and rotate to another clean one while it dries. If it gets too gross or for whatever reason toss it.
Quart size seltzer bottles (or tonic water or whatever comes in that type of bottle works great.
Dump out the water in the unit every once in a while and spray down with the alcohol and let it dry out.
You can get a humidity/temp sensor for ~$10 also, which can help you keep an ideal (35-45%) level of moisture.
Hope this helps.
I've been having the same problem. What I ended up doing is getting a little humidifier similar to this one https://www.amazon.com/PerfectAire-PAU1-Ultrasonic-Humidifier-360-Degree/dp/B00J4LN490/ref=sr_1_17?dchild=1&keywords=portable+water+bottle+humidifier&qid=1610738222&sr=8-17 and putting it on top of the enclosure. Depending on the setting, it raises the humidity 10-25%. Works kind of like a reptile fogger, but way cheaper. I also just found a big warm humidifier similar to this one https://www.amazon.com/Vicks-Humidifier-Filter-Free-Moisturized-V745A/dp/B001FWXKTA/ref=sr_1_5?dchild=1&keywords=warm+humidifier&qid=1610738438&sr=8-5 that I will be putting next to the tank. They can both be fairly pricy, but if you go to your local goodwill/salvation army/thrift store you can usually find one for like 5 dollars, and with a little cleanup, they're good as new! (Just be sure they have all the parts before you buy one!!) Also, if you haven't already, you can cover half of the top of the tank with aluminum foil and/or bubble wrap. Hope this helps!!