You need to tell us what you want because there are many options…
Do you want a shop air compressor with a big tank or a home garage unit with a small tank? Or is a Pancake unit what you want?
Are you looking for a 12v unit that can stay in the trunk for topping off or filling?
OR are you looking for a cordless inflator? What size tire are you filling and what it the operational pressure? For example a big tire at 90 PSI isn’t going to happen on a Walmart inflator, but a Honda Accord tore at maybe 35 PSI will top off from maybe 27 PSI in a couple of minutes.
I have ALWAYS had a battery powered inflator since owning my first car in 2002. The first unit was a Walmart special no-brand and it worked great but eventually got to the point it would run slow and struggle to get through a couple tires, and in 2009ish I replaced its internal sealed-lead-acid battery, lol! It works great until 2014 when a friend had an air tank and my dumb self let him fill it. I think it ran 25 minutes straight, was too hot to touch, hose bulging, and stinking of melted plastic. It still worked but was half as fast, and I replaced it wirh a campbell hausfeld unit that looked similar, and it was no faster and the battery life no better than the unit it was replacing. It struggled to top off 4 car ties 30 to 33 psi on a battery…. I thought it was a fluke and bought another one. It was crazy in that I would use 2 or three inflators at a time to top up tires.
Then in 2020 I was at an Aurocross and borrowed and M12 inflator and it ran circles around my setup probably being about twice as fast as the unit I once liked from 2002! so I bought one after watching Project Farm. From about 2018 to 2020, the M12 has been the very best cordless inflator compared against Bauer, Hart, Skill, Kobalt, Greenworks, Makita, a couple Chinese ones, and Dewalt it was MUCH faster than most and best all of those even the 18v and 24v models!
In 2020ish the Ridgid 18v inflater took the win. It was faster than the M12 by maybe 15%, it did good even at relatively high pressure, and Ryobi became just slower than the M12 but at $24 bare tool, if you have Ryobi batteries buy one! It has no auto shutoff but is still right behind M12 beating most $100+ units.
Early this year the M18 inflator came out and it is 1.5 to 2x faster than the M12 inflator. I bought it and it’s crazy fast. I can top up a car tire 27 to 35 in the time it takes me to take off the valuable stem cap on the next tire!
I have an M12 and an M18 inflator, and both are superb. I am probably going to buy the Ryobi at $24 to lend out. At work (I do IT networking), several folks know I have the M12 inflator and it has helped several. They are ALL impressed how effortlessly it takes care of the problem. Last week it took my car from 27 to 35 TPMS all tires, a work van 31 - 46 TPMS all around, a co-worker 29 - 36 TPMS all around Hyundai SUV, and a friend wirh a 2004 Toyota Corolla who came over to exchange some Thanksgiving gifts … it was obvious all tires were practically flat (no TPMS) and she shouldn’t be driving it that way…. That was 18 to 31 on all 4. It’s a workhorse! Yes I charged it somewhere in there, but it has never let me down!
This weekend I got an M18 inflator unit free by purchasing 2 batteries and a charger for $179 or $199 (cannot remember) at Home Depot. That machine is amazing and powerful and currently blows all other cordless units out of the water.
In order (best to worse) I would get these:
1. M18 inflator
2. Ridgid 18v Inflator
3. M12 inflator
4. Ryobi cordless inflator (looks like a drill)
The Ryobi probably won’t last the longest and has about a 5 minute duty cycle and you have to hold the trigger, but it’s 90% as fast as the M12 and about $24 bare tool. In tests it did pump to 90 PSI no problems on YouTube.
I would get the top three if you want years of reliable service…. The Ryobi is the I have a flat, a very low tire, need to fill my spare, my TPMS is on I just want to drive to work I flator
An air compressor is faster, but for convenience a cordless inflator is all you probably need.