Currently UK resident- may move home in future. ISA or pension

Hi
I'm in my 40's and don't have a pension. I hope to start this year.
I've been in the uK 7 years. I could be here for another couple of years or a lot longer.
I believe if I have a SIPP in the UK and move home I won't lose the tax benefits? However I might with an ISA. is this correct? Is a pension the better of the 2 to invest in ?

A supplementary question also. In the UK I can invest up to 40 k annually in a pension. I can also backdate 3 years.
I have a couple of investment properties in Ireland as well as my own flat in London and a 2 bed house at home. Is it wise to sell a RIP and use proceeds in the pension with the added tax benefits?I think I'm property heavy. I appreciate there may not be a simple answer.
Appreciate any thoughts.
Niall

Correct, you can transfer the benefits from a SIPP into a PRSA when you come back. I moved the contents of a Hargreaves Landsdown SIPP into a Davy Select PRSA myself a couple of years ago.

With regard to the ISA, you would lose the benefits of the tax wrapper when you no longer are tax resident in the UK however up until that point it would still be exempt of CGT/income tax. So when you'd move home you'd now have a portfolio that was no longer shielded from tax, hence I think the SIPP works better.

Thanks Dabeiri and apologies for delay!
Good advice- That's what I was thinking myself.