I tested it... it is definitely m/0' for the wallet I created today.
The "full" path to the first address is actually m/0'/0/0... Electrum seems to automagically add the first "0" when it starts looking for "receive" addresses... and then the 2nd "0" for address at index 0.
If you use bitcoinj and do a dump with --dump-privkeys, you'll see something like this right at the end of the dump:
addr:1K2rCAnAvqHETgG9rHrzysJ4PPue9Lr7EQ hash160:c5cbbe73ae2c4d1ce0eaaa5303b27d9c0d120292 (M/0H/0/0)
That is the address I see in the app when I click the QRCode to see my receive address... and the address that Electrum generates when I use m/0' as the derivation path when importing
For reference, the full dump of my testing wallet is:
Wallet
WARNING: includes private keys!
Balances:
0.00 BTC ESTIMATED
0.00 BTC AVAILABLE
0.00 BTC ESTIMATED_SPENDABLE
0.00 BTC AVAILABLE_SPENDABLE
Transactions:
0 pending
0 unspent
0 spent
0 dead
Last seen best block: 567262 (2019-03-16T01:11:02Z): 0000000000000000001da8b54a299a642ba92d50f0d20078f9781c1accd9be9d
Keys:
Earliest creation time: 2019-03-15T20:52:59Z
Seed as words: shed cruel trap raccoon planet lecture harvest night narrow grass surround noble
Seed as hex: 3bd7c9cc0397b3023ba83fcbd1deec5fef1c68a3ed947ee7a326f186fe005f5f6c58040d39df3f32864f4fb2b8557caa4bc41dde1e6b2eb639d0fa4ff5a45815
Seed birthday: 1552683179 [2019-03-15T20:52:59Z]
Ouput script type: P2PKH
Key to watch: xpub69G3fM82T2Xmx9VsUeeYWnmYRGGrQrD3pCe2msvVDf4MhRZ5j9HsnFmJvpMBmMX9wZJ8JdSwzU8am2MA8RSttzZ1eUEHMuVtCii9JkR7yLy
Lookahead siz/thr: 100/33
addr:1J1eAbKcRQTsgwzhn8buqUM8pPQ8A2duRm hash160:ba99299424eda8ed8b453835738850ade43fcea0 (M, root)
DeterministicKey{pub HEX=02f0a36dde523f7d7cff5232f3f0ddaf61778e40ee1c47cc3e8cb82b8c46300fa9, priv HEX=c8866c5513583249996bc6b0d05571d2322e7c7f85d6fdbe00fa47d966bbba57, priv WIF=L3wWGbkcaQeG5iCJcnJrXgwEovMLn2HsJktG4TqtvvH1c3hg4wbG, creationTimeSeconds=1552683179, isEncrypted=false, isPubKeyOnly=false}
addr:1LDUZuuv37oPWE1NU2EnFjvVVgrTEe3XtF hash160:d2c664c1efad9bb8ba6d44a5893bd7c911a67897 (M/0H, account)
DeterministicKey{pub HEX=03598fe12ea45f4f669242079f59b6233ec0a2ae3a73162bf650c8afebab0b2fd7, priv HEX=2a8c3c0b102a27142fffbc8d271f242ea246cbb3f4a797bef727c437508506aa, priv WIF=KxeRDArBfhAPyTmzQgRfDua5tX1p9ogh2an9B358sMbnMyNJfLSw, isEncrypted=false, isPubKeyOnly=false}
addr:14qUE7sA8ZvAYXsxi3RhmWfMVKvwjiYQLv hash160:2a13121f118f0861f5a9720601b5c2698564c2ec (M/0H/0, external)
DeterministicKey{pub HEX=039f5643f48c77d434bfbdbcac72fe72dfef272caf7db901a7932963b4ab041180, priv HEX=aca6d3c371812845e01af4ff6dfcf1a08aa69ade7d41a1d437827775c3f8658f, priv WIF=L31KhNsP3orEfLRZFAzTPAcuUa7HttyAN1iA3pTsU3DZjPAuZPTn, isEncrypted=false, isPubKeyOnly=false}
addr:1P1tUWAYAxv68wA8nfmXA1fjQUM6M3mdMF hash160:f17dbc58d385fc27047904337c3fe79f3421fdd2 (M/0H/1, internal)
DeterministicKey{pub HEX=034049298d152957146885596e731e5d94b80013558341fe82648562f19cb6e745, priv HEX=579c14f425a527cf9adfcdd4f58286dd9af9bc0586976c0e47dbcbd5e44880d8, priv WIF=KzA1guaT4BmrJsW7n4DFx7kn7BTMCLkEim3tnqbxd6Qeawdy1voR, isEncrypted=false, isPubKeyOnly=false}
addr:1K2rCAnAvqHETgG9rHrzysJ4PPue9Lr7EQ hash160:c5cbbe73ae2c4d1ce0eaaa5303b27d9c0d120292 (M/0H/0/0)
DeterministicKey{pub HEX=02269536b52e9f2ca55b60f191b04fee96454fc9c7da046e2520cf0723456cafed, priv HEX=9b32a1c99c54379935bef01c8ab56015f7280337e7f200b50db8f1c9166c03cc, priv WIF=L2RPsKyWe1pERXbxLRmNJrT99Uv25nJokNNLCf6TsSZ4jQKdoavV, isEncrypted=false, isPubKeyOnly=false}