https://mempool.space/

Cant go wrong with Mempool.space. The blocks are nicely lined-up and move when the new one is mined. Pretty colours and some nice stats! Made with a lot of love and it shows!

https://bitfeed.live/

Transactions fall tetris-like calmly in their spot. You see the mempool fill up and once the block is mined something magical happens and all the transaction transform into this colourful block. My favourite!

https://timechaincalendar.com/

Cool one-pager with all the timechain info you need. You can even go back in time to see what block was mined at a specific date and time!

https://txstreet.com/v/btc

The mempool, but then as a crowded bus station. Cartoonish and fun to watch!