
Segway
Ninebot Max G3
Durable hill-climber; heavy with limited range.

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I really like my Air X, but I try to prevent driving over cobblestone with it, unpleasant and risky for the carbon frame.
I dunno, I have the Air X and it's pretty good. Actually it climbs like the Etwow GTS. And I always turn and take a last look at it after parking, so that's gotta be something ....
I've had my KQi Air for over a year, and have been pretty happy with it. There was one time when the battery gradually gave out on me while on a ride, and I had to walk it back to the house. I believe it was related to the fact that I cap the charge at 85%, and the on-board battery meter isn't entirely reliable. Also, you can never shut these things completely down, so make sure you charge them occasionally even when stored away.
You can basically only put the scooter to sleep, and when in sleep mode, it still draws enough power from the battery such that it will drain completely in a month or so. So if you're constantly using it, this shouldn't be much of a concern. But if you plan to stop riding it, during the winter for instance, then you need to remember to occasionally top it off.
This was actually my first electric scooter, so I don't know if this power management behavior is typical. Somebody from NIU did comment in this thread, so maybe they have some insight into whether these scooters could ever be updated to go into full shut-down mode. Though given that I've seen this issue come up in these discussions before, I think any changes would be reflected in a newer model instead of one that has already been out for some time. $599 is a great deal on this particular scooter. I paid above $1k for mine initially, but then got reimbursed a bit when it went on sale shortly after. Its light weight is its main selling point - I'll literally hang it off my shoulder while grocery shopping. Of course, the light weight means its built-in security features (alarm and locked wheel) are somewhat useless since someone could just pick it up and toss it in the back of their car. I tend to not carry a lock, but the businesses in my area don't seem to mind when I park it inside - it's not as massive or intimidating as some of the other scooters out there.
I’ve had my air for 6mo and love it. Got it because of the portability, and it would be a drag carrying anything much heavier around tight corners or up steps regularly. Speed and distance are as much as I would ever need. It’s got no suspension, so you feel all of the bumps on rough surfaces, but smooth roads are fantastic. I was in a hotel for a month and could Cary it in the door and up the elevator with no problem.
and BTW I think the KQI# air is still the most brilliant e scooter on the market
Just flagging that weight can be an issue if you are going over 25mph as the batteries will be larger and most have pretty robust suspensions to accommodate those speeds. Bigger battery + suspension = weight. The niu scooters are great IMHO. Nothing fancy but they get you from point A-B. The KQI# air is an awesome scooter as it only weighs 26lbs, can go 20mph and has pretty good range. KQI 300p has some suspension 24mph and great range at 45lbs. Segway are seen as very reliable. The g2 (last years model) is great 22mph, good range and 53lbs. The G3 (updated model is a bit faster and about the same weight. As you add more speed and range the weight will go up considerably. Some of the recs you are getting already are for scooters that are creeping into the 75lb+ range. So flagging - if you want to transport the scooter in a car or truck consider the weight and size.
RS6 ultra 2900. What I bought. Upgrading from a Nui Kqi

Segway
Ninebot Max G3
Durable hill-climber; heavy with limited range.

Ausom
DT2 Pro
Budget speed demon with hydraulic brakes; slow charging.

Inmotion
Climber
Hill climbing champ, great value, but lacks suspension.

Segway
Ninebot KickScooter MAX G30P
Durable, mod-friendly value, but lacks suspension; tire changes hard.

Segway
Ninebot MAX G30LP
Durable, budget commuter, but slow on inclines and no suspension.

Ranked #1
Inmotion - Climber

Ranked #1
Inmotion - Climber

Ranked #1
NIU - KQi Air

Ranked #1
Segway - GT3 Pro

Ranked #1
Segway - ZT3 Pro

Ranked #1
Segway - Ninebot Max G3