The g303 currently has the best sensor on the market besides the g502 but the g502's design is also not great
Mice I would currently reccomend:
DA 2013/Chroma or w/e
Zowie FK1 or ZA series
Steelseries Rival 100 if you have really thin hands
Mionix Castor
The DA has pretty good ergonomic shape, isn't too expensive, is an overall solid mouse with solid sensor, really just depends if you want to deal with razer products (i.e synapse)
Zowie FK1 and ZA series are both great, flawless sensors with good build quality and no driver crap but have huano switches which are a lot stiffer to click compared to just about every other mouse out there, also lean towards the expensive side, shapes are both good just depends how big your hand is
Rival 100 has solid build quality, price, and good sensor but has odd DPI steps compared to most mice and the shape/design of the mouse is very thin and the buttons are placed very far down the mouse making it uncomfortable imo but it could suit you
The Castor has pretty some of the best build quality of any mice I've ever used, flawless sensor, solid mouse design and shape, no wonky software or dpi steps, but also the most expensive or one of the most expensive mice on this list
It's a shame the g303's shape is so bad because it would be my all time favorite mouse if it wasn't