The Monero and Bitcoin transaction fees are very close to each other. There is not practical difference, exept during the high volume times Bitcoin has had actually higher fees.
https://bitinfocharts.com/comparison/monero-transactionfees.html
https://bitinfocharts.com/comparison/bitcoin-transactionfees.html

Also, the Transaction fees of Monero will be decresed even more by 80-90% by the bulletproofs.
https://ethereumworldnews.com/monero-bulletproof-protocol/
https://getmonero.org/2017/12/07/Monero-Compatible-Bulletproofs.html

In addition The Tari Project which is a second layer protocol for Monero, will cut the transaction fees to fractions by Lightning Networks. It will also bring Atomic Swaps, Internal assets and much more for Monero.
https://www.tari.com/

The "not fixed" supply is not a problem at all. There is a fixed tail emission for Miners to have an incentive to mine. And because the tail emission is fixed, the emission in relation to existing supply will be decreasing. Also, the tail emission will be very low. 0,6XMR per 2 minutes block. That is only 432XMR per a day.
https://getmonero.org/resources/moneropedia/tail-emission.html

Also, the Tari Protocol will be merge Mined with Monero.