Depends if we are talking lithium hydroxide or lithium hydroxide...

Depends if we are talking lithium hydroxide or lithium hydroxide monohydrate. If talking the latter, just be mindful that the spodumene input 'perceived' is slightly lower in producing lithium hydroxide monohydrate than lithium carbonate. I explained that in this post Post #: 37277249:

1.0 From the above embedded post initalics below
"Lithium carbonate (Li2CO3) has a Li content of 18.8, so need about 7.5 tonnes of 6% grade spodumene at a 90% recovery rate in the roasting process.

Lithium hydroxide monohydrate (LioH.H20) has a Li content of 16.5%, so need about 6.5 tonnes of 6% grade spodumene at a 90% recovery rate. Lithium hydroxide (LioH) has a Li content of 29%, so need about 11.5 tonnes of 6% grade spodumene at a 90% recovery rate.

If recovery is lower - I also understand it could be 85% - then your spodumene input is higher etc.

The reported price for hydroxide is lithium hydroxide monohydrate (min 56.5% LioH.H20, meaning the other 44% is presumably water theoretically), compared to carbonate which prices are based on 99.5% -Li2C03. I suspect your monohydrate comes from the more purer form of hydroxide (LioH), that is then ineffect 'reacted' in process to get to your commercially graded monohydrate (LioH.H20 - battery grade I guess) which is the reported prices. It is probably where my confusion is as I always think of lithium hydroxide as LioH instead of the monohydrate of LioH.H20, and assume the former is derived first before deriving the latter (monohydrate). Probably I need to do more research to get a better understanding of the hydroxide process for getting to monohydrate etc."

2.0 Is hydroxide preferred- your question ineffect

I still think you can use LCE (this is actually a term that converts lithium chemicals whether they be hydroxide or something else to a Lithium Carbonate Equivalent so makes forecasting better). The market at the moment is wanting hydroxide for batteries and this is the domain of hard rock IMO. There will always be a role for brine or even lower grade hard rock deposits for the products that are ultimately produced from lithium carbonate. But you are correct, lithium hydroxide is preferred and currently grade is king in that market and the best hydroxide is produced from high grade hard rock operations. It is why in part I can see an entry point for AVZ in the market provided it gets its act together. Without going over old ground I yabber about hard rock in the growing hydroxide market in this post done ages ago i the embedded posts below.
Post #: 25812318
Post #: 25816692
Post #: 31661029

The LCE forecasts themselves don't have a breakdown between hydroxide and carbonate, so would be difficult to do in any event (but if others would like to have a go that would be good). And obviously lithium carbonate still has applications in certain applications and/or where consumers don't mind having lower quality batteries to those produced from hydroxide. Consumer choice and use in applications will be influenced in part by the price differential between carbonate and hydroxide balanced by the benefits associated with say a consumers viewpoint on the benefits of having a higher quality battery.

All IMO IMO but obviously others may have a different viewpoint which they may want to share here.