By Madara I'm assuming you mean Edo Madara. I'd choose Edo Madara because he's currently OP/indestructible atm. If you meant alive Madara, then I'd choose Hashirama.

If Obito really can use all rinnegan abilities with one eye then i give it to Obito. Kamui + Rinnegan = rape
Anybody saying Madara is delusional. Edo Madara is not Madara. His prime is VoTE which was promptly defeated by Hashirama. Edo Madara is modified WAY beyond his prime.
EMS+Rinnegan+Mokuton vs EMS? Clear difference. You can't consider Edo Madara.
Hashirama is number 1. It is debatable at number 2, with Obito and EMS Madara close, but I'd say Obito. Current Obito probably has more chakra than EMS Madara and can promptly dodge all of EMS Madara's attacks. Again it is debatable, but number 1 is not.