Among the RE 350s, you can consider the Hunter / Bullet / Classic models for their comfortable ride, neutral ergonomics and smooth as well as characterful engine. In a similar vein, the Honda CB350s also warrant strong consideration for similar reasons. 

All the Harley-Davidson X440 models have a similar riding experience and only differ in terms of features and design, so pick the one you like the most. 

Lastly, we would also recommend you take a look at the Triumph Speed T4 and Triumph Speed 400 as they offer great performance and quality at a reasonable price. 

Take a test ride of all the bikes you shortlist before you decide. 

We would advise you to look at other options than the Royal Enfield Bear 650 because we found the rear suspension to be very stiff in our time with it. This means that on less-than-perfect city roads, your back will bear the brunt of the bumps, which won't be ideal given your long daily commute.

Instead, we would recommend you look at the Royal Enfield Himalayan 450 because it has much better suspension comfort and will have exciting performance while also fitting in your price range. 

If your heart is set on a 650cc bike, then the Royal Enfield Interceptor 650 is the best bet for city use with its supple suspension, neutral ergonomics and creamy smooth engine. 

Take a test ride and decide before you buy. 

Since you are used to a good amount of performance, we'd suggest you move to something like the Triumph Speed 400. This bike will meet your needs of having a comfortable riding position as well as a reasonably low seat height. 

There are more comfortable options available, but almost all of them are adventure bikes with relatively tall seats. If you can get along with a taller seat, we'd recommend options like the Royal Enfield Himalayan 450 or KTM 390 Adventure as good replacements for your Aprilia RS 457. 

Of the options you've shortlisted, the Royal Enfield Himalayan 450 will be the best all-rounder with good highway manners, plush suspension for rough roads, and it's usable inside the city too, although its weight and general size need to be kept in mind. 

The Meteor 350 and Triumph Scrambler 400 XC will be better in the city than the Himalayan, but out on the highway, your comfortable cruising speeds will be capped at 80-100kph. Take a thorough test ride before you decide.

Since you seem to have had a lovely experience with the Hunter, and if you want to stay within the Royal Enfield fold, the Himalayan 450 makes for a great option for your sort of usage. 

If you find it too big and heavy, the Royal Enfield Guerrilla 450 can be considered because it weighs as much as the Hunter but has a far higher performance and capability ceiling. If you want to look elsewhere, then the KTM 390 Adventure models (both the X and standard) are good options in the ADV space. The 390 Duke is a great option if you want a sportier machine. 

Do decide if the aggressive and polarizing new KTM design philosophy is for you after the clean and pleasing lines of your Hunter. If you want something like the KTM 390 Duke without the in-your-face looks and colours, the Husqvarna Svartpilen 401 is mechanically identical to the Duke but has a far more pleasing aesthetic and is also more spacious. 

Since you've cut your teeth on the Himalayan 450 for quite a while now, stepping up to a twin-cylinder offering like the Himalayan 750 or BMW F 450 GS is a good bet. 

We would recommend a thorough test ride of both machines once they are launched, and would also advise you to wait some months after their launch before making your purchase.