This is a list of ssh based device_types that netmiko accepts (Retrieved 2020-02-17 - https://github.com/ktbyers/netmiko/blob/develop/netmiko/ssh_dispatcher.py)
Some of these also have telnet support by appending _telnet to the end of the device_type
a10 -- A10SSH
accedian -- AccedianSSH
alcatel_aos -- AlcatelAosSSH
alcatel_sros -- NokiaSrosSSH
apresia_aeos -- ApresiaAeosSSH
arista_eos -- AristaSSH
aruba_os -- ArubaSSH
avaya_ers -- ExtremeErsSSH
avaya_vsp -- ExtremeVspSSH
brocade_fastiron -- RuckusFastironSSH
brocade_netiron -- ExtremeNetironSSH
brocade_nos -- ExtremeNosSSH
brocade_vdx -- ExtremeNosSSH
brocade_vyos -- VyOSSSH
checkpoint_gaia -- CheckPointGaiaSSH
calix_b6 -- CalixB6SSH
ciena_saos -- CienaSaosSSH
cisco_asa -- CiscoAsaSSH
cisco_ios -- CiscoIosSSH
cisco_nxos -- CiscoNxosSSH
cisco_s300 -- CiscoS300SSH
cisco_tp -- CiscoTpTcCeSSH
cisco_wlc -- CiscoWlcSSH
cisco_xe -- CiscoIosSSH
cisco_xr -- CiscoXrSSH
cloudgenix_ion -- CloudGenixIonSSH
coriant -- CoriantSSH
dell_dnos9 -- DellForce10SSH
dell_force10 -- DellForce10SSH
dell_os6 -- DellDNOS6SSH
dell_os9 -- DellForce10SSH
dell_os10 -- DellOS10SSH
dell_powerconnect -- DellPowerConnectSSH
dell_isilon -- DellIsilonSSH
endace -- EndaceSSH
eltex -- EltexSSH
eltex_esr -- EltexEsrSSH
enterasys -- EnterasysSSH
extreme -- ExtremeExosSSH
extreme_ers -- ExtremeErsSSH
extreme_exos -- ExtremeExosSSH
extreme_netiron -- ExtremeNetironSSH
extreme_nos -- ExtremeNosSSH
extreme_slx -- ExtremeSlxSSH
extreme_vdx -- ExtremeNosSSH
extreme_vsp -- ExtremeVspSSH
extreme_wing -- ExtremeWingSSH
f5_ltm -- F5TmshSSH
f5_tmsh -- F5TmshSSH
f5_linux -- F5LinuxSSH
flexvnf -- FlexvnfSSH
fortinet -- FortinetSSH
generic_termserver -- TerminalServerSSH
hp_comware -- HPComwareSSH
hp_procurve -- HPProcurveSSH
huawei -- HuaweiSSH
huawei_vrpv8 -- HuaweiVrpv8SSH
ipinfusion_ocnos -- IpInfusionOcNOSSSH
juniper -- JuniperSSH
juniper_junos -- JuniperSSH
juniper_screenos -- JuniperScreenOsSSH
keymile -- KeymileSSH
keymile_nos -- KeymileNOSSSH
linux -- LinuxSSH
mikrotik_routeros -- MikrotikRouterOsSSH
mikrotik_switchos -- MikrotikSwitchOsSSH
mellanox -- MellanoxMlnxosSSH
mellanox_mlnxos -- MellanoxMlnxosSSH
mrv_lx -- MrvLxSSH
mrv_optiswitch -- MrvOptiswitchSSH
netapp_cdot -- NetAppcDotSSH
netscaler -- NetscalerSSH
nokia_sros -- NokiaSrosSSH
oneaccess_oneos -- OneaccessOneOSSSH
ovs_linux -- OvsLinuxSSH
paloalto_panos -- PaloAltoPanosSSH
pluribus -- PluribusSSH
quanta_mesh -- QuantaMeshSSH
rad_etx -- RadETXSSH
ruckus_fastiron -- RuckusFastironSSH
ruijie_os -- RuijieOSSSH
ubiquiti_edge -- UbiquitiEdgeSSH
ubiquiti_edgeswitch -- UbiquitiEdgeSSH
vyatta_vyos -- VyOSSSH
vyos -- VyOSSSH
watchguard_fireware -- WatchguardFirewareSSH