It’s hard to recommend any one watch since besides the cost it really depends on your use and personal tastes. I’ve listed some watches below that are a good starting point and some that have a historical association with Aviation.
Casio F-91W
Classic Casio watch, it does it’s job well, pretty cheap and really can’t go wrong.
Casio GA 2100 1A1
G-Shock with but a thinner profile and slightly refined designed. Takes some design cues from the Royal Oak.
Seiko 5
They have a good reputation given the price. Keep in mind even though it’s a cheaper movement, all mechanical watches will require servicing at some point. I would personally just wear a quartz at price point unless you really want an automatic movement.
Omega Speedmaster Professional
An Iconic timepiece, reliable and proven movement, if I could only ever own one watch this would be it.
Rolex GMT Master II
Originally designed for Pan Am pilots, useful if you regularly travel across time zones. There’s a lengthy wait list for this watch if you want to purchase it through an authorised dealer.
IWC Mark XVIII
Current evolution of the original Mk XI manufactured for the British MoD, it’s simple and reliable.
If you like the style of the Seiko 5 you mentioned, Sinn and Hamilton also make quality timepieces. Sinn in particular has a number of aviation watches. There are a few other manufacturers that make the Flieger style watches that originated in Germany.