It would be preferable to use Custom binding if you want to use certificate based authentication while using SOAP 1.1(Also considering interoperability like Java based clients or oracle services). AuthenticationMode would change based on your needs.
For example, the below binding shows Mutual certificate authentication on both server and client side + transport security(https).
<customBinding>
<binding name="customSSLMutualCertificate" sendTimeout="00:05:00" receiveTimeout="00:05:00">
<customTextMessageEncoding messageVersion="Soap11"/>
<security defaultAlgorithmSuite="Basic256Rsa15" authenticationMode="MutualCertificate"
requireDerivedKeys="false" securityHeaderLayout="Lax" includeTimestamp="false"
keyEntropyMode="CombinedEntropy" messageProtectionOrder="SignBeforeEncrypt"
messageSecurityVersion="WSSecurity11WSTrustFebruary2005WSSecureConversationFebruary2005WSSecurityPolicy11BasicSecurityProfile10"
requireSignatureConfirmation="false" enableUnsecuredResponse="true">
<localClientSettings cacheCookies="true" detectReplays="false"
replayCacheSize="900000" maxClockSkew="00:05:00"
maxCookieCachingTime="Infinite"
replayWindow="00:05:00" sessionKeyRenewalInterval="10:00:00"
sessionKeyRolloverInterval="00:05:00" reconnectTransportOnFailure="true"
timestampValidityDuration="00:05:00" cookieRenewalThresholdPercentage="60" />
<localServiceSettings detectReplays="true" issuedCookieLifetime="10:00:00"
maxStatefulNegotiations="128" replayCacheSize="900000" maxClockSkew="00:05:00"
negotiationTimeout="00:01:00" replayWindow="00:05:00"
inactivityTimeout="00:02:00"
sessionKeyRenewalInterval="15:00:00" sessionKeyRolloverInterval="00:05:00"
reconnectTransportOnFailure="true" maxPendingSessions="128"
maxCachedCookies="1000" timestampValidityDuration="00:05:00" />
<secureConversationBootstrap />
</security>
<httpsTransport manualAddressing="false" maxBufferPoolSize="524288"
maxReceivedMessageSize="65536" allowCookies="false"
authenticationScheme="Anonymous"
bypassProxyOnLocal="false" hostNameComparisonMode="StrongWildcard"
keepAliveEnabled="true" maxBufferSize="65536"
proxyAuthenticationScheme="Anonymous"
realm="" transferMode="Buffered"
unsafeConnectionNtlmAuthentication="false"
useDefaultWebProxy="true" requireClientCertificate="false"/>
</binding>
</customBinding>
Also refer Does WCF support WS-Security with SOAP 1.1? for other options