I have a lot of fountain pens, some very high end, some cheap garbage. The TWSBI Echo is my favourite pen to write with. The nib is dreamy. Pare that with J.Herbin ink and it's the best writing experience I've ever had.
TWSBI leans towards the thicker side for me personally, but it's a great workhorse pen for anyone who uses fountain pens daily on real writing tasks. TWSBI Eco's ink reservoir size and ease-of-use is simply unrivalled among competitors in the same price range.
Lamy Safari has been my go-to for years, but for anyone starting out I recommend the TWSBI Eco. Only downside imo is inability to easily swap out nibs in a TWSBI.
I'll second this recommendation!
The TWSBI Eco is a beautiful, robust, and dependable pen.
The TWSBI pens definitely hit a sweet spot for me as well.